Studies are examining the role of estrogen and progesterone-regulated gene expression in the control of morphological and neurochemical events in the ventromedial hypothalamus of the female rat brain and the relationship of these events to the hormonal control of female reproductive behavior. Experiments are designed to examine sex differences in these estrogen and progesterone regulated events and the role of sexual differentiation in these differences. Also in progress are studies examining the effects of adrenal steroids on the neurochemical adaptation of the brain to stress. Neurochemical studies of adenylate cyclase activity and mRNA; CRF and vasopressin mRNA and peptide level; and tyrosine hydroxylase mRNA and enzyme level as they are influenced by stress and glucocorticoids. Studies of the mechanism of dendritic atrophy caused by glucocorticoids and stress, using serotonin and glutamate neurotransmitter receptor blocking drugs. Studies of the efficacy of antidepressant drugs on these same endpoints. Also being conducted are studies examining mineralocorticoid and glucocorticoid control of salt appetite via effects on angiotensinogen, tachykinin, oxytocin and vasopressin gene expression. Localization of receptors which respond to mineralocorticoids and glucocorticoids, using immunocytochemistry, in situ hybridization and western blotting.